@thiagogabriell 

Hello, thanks for reporting the issue but please provide some details about the auto-reboot issue then we will try to investigate and offer a solution ASAP.

When the router restarts, are all the LEDs turn off then on automatically and the internet on it will temporarily down then recover? How long does this process take?

May I have your network layout, how is the WR941HP connected to your network? Are there any other range extenders or switch in the network? If yes, try to remove it first and confirm again.

Who is your ISP and what kind of modem are you using? Is it a Dynamic IP setup on the WR941HP WAN or PPPoE? 

How many devices are connected to WR941HP, wired, and wirelessly? What are they? Is there any new device connected to the WR941HP network recently when the WR941HP begins to reboot? Or did you upgrade any system in the network before this issue happen?

Is there any other setting or feature in your network that may cause this restart issue, or is there any special operation/activity in your network that causes the WR941HP to restart, such as high loading or real-time calls? 

Is it the original power adapter on the WR941HP? Is the power stable in your house? How about other electrical devices in your house, are they stable?

Does this issue happen when you purchased it or happens recently? Try to reset the router to factory defaults and reconfigure it from scratch, then confirm again.